Rheostat.



F. D. HALLOGK.

RHEOSTAT.

APPLICATION FILED JULY 6, 1908.

Patented May 24, 1910.

3 BHEETSSHEET 1.

DLINVENTOR ATTORNEY WITNESSES: @Mo q MW F. D. HALLOGK.

RHBOSTAT.

APPLICATION FILED JULYG, 190s.

Patented May 24, 1910.

SEEKERS-SHEET 2.

Q IN ENTOR WITNESSES: $649M ATTORNEY F. D. HALLOOK.

RHEOSTAT. APPLICATION FILED JULY 6, 1908. 958,869. Patented May 24, 1910.

3 SHEETS-SHEET 3.

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WlTNESSES: m men ATTORN'EY UNITED STATES PATENT clement FLETCHER D. HALLOGK, or PITTSBUBG, PENNSYLVAhI-IQA, eggiliqidit, fiv nrnsn'ii as: SIGNMENTS, To wns'rmenouss ELECTRIC & manornceosms coMPANY, or EAST PITTSBURG, PENNSYLVANIA, A oonrozmr'ron' or rn'fi'itsiz'nvanm.

assesses. 1

Specification Letters Patent.

- Patented May 1916.

' To all whom it my concern: a

Be it known that I, FLETCHER D. .HAn- LOCK, a citizen of the United States, and a. resident of Pittsburg, in the county of Alic gheny' and State of Pennsylvania, have mventcd a new and useful Improvement in Rheostats, ofwhich the following is a specification.

My invention relates to rheostats, and particularly to such rheostats as are employed for the purpose of starting electric motors and governing the speeds of operation thereof.

The object of my invention is'to provide a cordance with the present invention, the,

circuit connections of the device'being illustrated diagrammatically. Fig. 2 is a. view in side elevation of the rheostat shown in Fi 1, and Fig. 3.is a face view of'a modifled form of the rheostat.

concentrically and pivotally mounted upon a panel or face-plate 1 are two arms 2 and 3 provided, respectively, with 9. lug 4 and an extension'5 thattm'e adapted to-en-.

gage each other in order that movement of the armfi from left to right may hc'cfi'ected by the ar1n.2, and movementof the arm 2 from right to '.left may be effected by the arm 3, a spring 6 being seated in the lug 4 for the purpose of cushioning the blows of the arm .3upon the arm 2. The arm 2 is freely movable and is provided with an opersting handle 7, whereas the arm 3 is constrained or biased in the usual manner, by means of a spring 8, toward its initial position, shown in broken and dotted liucs'in' Fig. 1.

The arm 2 is provided with a brush 9 adapted to engage two rpws or sets of sta -tionary contact terminals 10 and, 11 that are mounted upon the face-plate. 1 concerttrically with the pivotal connection thereto spectiv'ely, to suitablepoints of subdivision winding of which the arms 2 and 3.

of the t is 2 and .3, and are sweetenersof two resistances 12 and 13, the said sistauces being included, respecti vely, ,ih on? cuit with the field magnet wind-mgr; and. the armature winding 15 of an electric motor.

The arm 3 carries a flexible contact-memso her 10 that is adapted to enga e aoonducting ring segment [17 mounted upon the faceplat 1 concentrically with the arm? 3, the so; 'seg ment being connected to a terminal 18 that is also connected to one e 'tre'mity of the resistance 12., The se nenZlT-is' engaged by the member 16 only urin" ji'i'o'x' einiit of the arm 3 from the first to te nest-to the last 1esistaneego'verning po'sition,.the'n1ember is engaging, in its final positicn', a terminal at button 1-9 thatis connected to one extremity of the resistance 13 and to a terminal 20 to which one terminal of the motor armature is connected. Pivotally mounted upon the'iirni 34% iii armature 21 foran emetic-magnet 22 the is here shown as connected between two terminal-s 23 and 2 kt are ad tedto be connected, respective-1y, to the "j con actors of a suitable supply circuit. The winding of theelectro -magnet cann 'however, be oonn'ec'tedein such other desired and suitable arrangements that the arm 3 maybe retained in its final positionexcept ilpou failure of the line voltage or uponthe'occurrenceof other abnormal circ'uit conditions. The terminal 23 is also connected to The free end of the arm 2 is provided with an extension 25 that is ndu )ted to engage 90. a pivotally mounted terminal device 26 and to rec -vc the arcs that occur upon interruption f the circuits'and to thereby protect the terminals 10 and 11 and. the brush 9 from such ares, the. said device 2G-being normally maintained in its centralposition by means of a spring 27 and being connected to the'extre nities of the resistances 12 and 13.

The arms 2 and 3 normally occupy the positions shown in bjolten and dotted lines in Fig. 1, the circuits .of the motor being then interrupted. In order to start the motor, the arms 2. and 3 should bWItlOVd from left in right. When the member 16 engages the segment 17 the field resistance. 12 is short-circuitcd and the only 'efiect of the of the arm 2 independently and the armature resistances,

movement of the arms 2 and 3 is to gradually remove the resistance 13 from the armature circuit. However, .when the arm 3 occupies its final position and the member 16 engages the button 19, the field resistance 12 is no longer short-circuited, and the field strength may then be adjusted bty movement the arm 3 to any desired position, the arm 3 being retained in its final position by the attraction of the electro-magnet- 22 for the armature 21, and the armature resistance 13 being then entirely removed from the circuit. Thus, it is seen that the arm 2 controls both the field but that the construction and arrangement of the parts is such that the said arm is elfective to adjust only one'of the resistances at a time, 2'. e., first the armature resistance and then the field resistance.

If the voltage of the supply circuit falls below a predetermined value, or if other circuit conditions to which the electro-magnet 22 may be adjusted become abnormal, the armature 21 will be released and the spring 8 will return the arm 3 to its initial position, which carries with it also the arm 2. During the return movementof the two arms, the field magnet windin 14 is included in a closed circuit with 0th of the resistances 12 and 13 and the armature 15, and the field discharge may thus occurwithout injury to the winding.

The construction shown in Figs. 1 and 2 is particularly adapted for emplo ment when comparatively small amounts oi current are to be handled, but for controlling motors of large sizes, I prefer to employ a somewhat modified construct-ion (Fig. 3) in, which a brush 30 is employed for short-oircuitingthe armature resistance when the springactuated arm 31 occupies, and is retained in,

its final position, the segment 32 extending over substantially the same angular distance as the contact terminals that are connected to the armature and field resistances. In- Fig. 3, also, the winding of eIectro-magnet 33, whereby the arm 31 is retained in 1ts final position, is connected in series with field, magnet winding 34 of the motor controlled by the rheostat. The rheostat of Fig. 3 differs in other minor respects from'that of but its mode of operation is understood upon an inspection of the drawing, thus rendering 1t unnecessary to describe it more in detail.

season I claim as my invention:

.1. The combination with a movable member and two resistances adapted to be controlled thereby, oi a second movable member, means operatively connecting the said members to cause the same to move together in one direction and permitting independent movement of the resistance governing mem- .ber in the opposite direction, a stationary conducting segment, a contact device carried by the second movable member and engaging the stationary segment for a greater ,portion of the travel of the said member to short circuit one of the resistances, and means carried by the said second movable member for short-circuiting the other resistance at one of the limits of the travel of the said member.

2. The combination with a dynamo-elem tric machine having field and armature circuits and a -resistance for each of said circuits, of a movable member'controlling both of said resistances, a second movable member, a conducting se ment, a contact device carried by the secon movable member and engaging the stationary segment during the greater portion of the travel of the second movable member to short circuit the field resistance, and means carried by the second movable member for short-circuiting the armature resistance when the said member occupies one of its extreme positions.

3. The combination with a dynamo-electrio machine having field andarmature cir- 'cuits and a resistance for each of said circuits, of amovable member controlling both of-said resistances, a second movable member, means for retaining the second. member in its extreme position during the cont nuance of normal circuit conditions, a stationary conducting segment, a contact device carried by the second movable member and engaging the stationary segment during movement of the said'second member after it is in its extreme position to short circuit the field resistance, and means carried by the second movable member for short'circuiting the armature'resistance when the said member occupies its extreme posltion.

In testimony whereof, I. have hereunto subscribed by name this 30th day of June, 1908.

FLETCHER -Wit1iesses: H. C. Nacnn, Bnnm'r Hmns.

D. HALLOCK. 

